DBA’s New Best Friend: Oracle Database 10g and 11g SQL Performance Analyzer Prabhaker Gongloor (GP) Khaled Yagoub Pete Belknap Database Manageability Group

Outline SQL Performance Analyzer (SPA) – Introduction Recommended Testing Methodology Usage Scenarios – Evaluating Changes on Production System – 10.2  11g DB Upgrade SPA Exadata Simulation SPA Enhancements in Oracle Database 11g Release 2 Conclusion * Please visit us at the OOW Demogrounds Moscone West – D61/62

SPA Motivation Businesses need to adapt to changes to stay competitive, compliant and evolve – DB upgrades, schema, optimizer statistics refresh – SQL performance regressions: #1 cause of poor system perf. Current testing landscape and limitations – Expensive capture, partial workload, non-production optimizer context, binds – Large workloads (100Ks SQL stmts are common) – Manual and time consuming testing and regression tuning – No end-to-end testing solution – Test In Production is not too uncommon SQL Performance Analyzer (SPA)  Proactively detects ALL SQL regressions, BEFORE actual change is deployed  Integrated comprehensive solution for end-to-end SQL workload testing

SPA Overview Helps users predict the impact of system changes on SQL workload response time Low overhead capture of SQL workload to SQL Tuning Set (STS) on production system Build different SQL trials (experiments) of SQL statements performance by test execution Analyzes performance differences Offers fine-grained performance analysis on individual SQL Integrated with STS, SQL Plan Baselines, & SQL Tuning Advisor to form an end-to-end solution Analysis Report Compare SQL Performance SQL plans + stats Pre-change Trial Post-change Trial SQL Workload STS

SQL Trials SQL Trials capture execution performance (plans and statistics) of the STS under a given environment SPA Trials handle the SELECTS and query part of DML, DDL is skipped There are 3 methods to build SQL Trials: – Execute SQL Locally or Remotely Test execute statements in actual environment For remote execution, database link needs to be specified – Generate Plans Locally or Remotely Generated execution plans have bind visibility, so better than vanilla “explain” Quick way to check if wide-spread changes to SQL plans – Build from STS Convert STS to SQL Trial Use for SQL centric analysis with DB Replay or other testing tools Use for 9i/10.1 upgrade to higher releases

SPA: Common Usage Scenarios Database upgrades and patch-set releases – 9.2/10.1  10.2 or 11g releases – x  y or 11g releases Optimizer statistics refresh Database parameter changes Database schema changes (e.g., add/drop indexes) Implementation of tuning recommendations I/O subsystem changes (e.g., ASM, Exadata) SPA can be used for:  any change that affects SQL execution plan & performance  in production as well as test environments Information for use cases on OTN/ML Note: OTN

SPA: Enterprise Manager Interface Rich GUI through Enterprise Manager – New workflows added! DBMS_SQLPA package PL/SQL API New Workflows !

Recommended Testing Methodology

Real Application Testing: Recommended Methodology 2. USE DB REPLAY FOR LOAD / CONCURRENCY TESTING DONE? No DEPLOY CHANGE & TUNING Yes No DONE? 1. USE SPA FOR SQL RESPONSE TIME / UNIT TESTING

Recommended Testing Methodology with SPA 1. CAPTURE REPRESENTATIVE SQL WORKLOAD TO STS 3. MAKE CHANGE, ESTABLISH SQL TRIAL-N 2. ESTABLISH BASELINE (SQL TRIAL-1) WITHOUT CHANGE 4. COMPARE TRIALS & REVIEW SPA REPORT, REMEDIATE Reports show deviations from production No Yes 5. Deploy Change & Tuning to PROD OR further testing thru DB Replay Compare Baseline to Trial-N in the same environment For incremental tuning: Compare Trial N-1 to Trial-N Test one change at a time to understand causality DONE? Use Production or identical Test System

Usage Scenario: Evaluating Changes On Production

+Parameter Change 1. Fix Regression thru SPM +Add indexes Using SPA For Changes in Production: Example Fix Regression SQL Profile Prod +SQL Profile +New Stats Change +Partitioning +Validate Tuning Parameter change was bad in this case And so on… +Index Unusable Bubble following the arrow indicates the delta change on Production SPA is used for testing every change

How to Minimize Impact on Production? Generate Plan Vs Test Execute – Use Generate Plan Trial Method to subset SQL with plan changes – Only test execute SQL with plan changes Limit testing scope to private session or schema where possible – Use alter session set = ; (Vs system) – Example usage for SQL Profiles: alter session set sqltune_category= ‘TEST’; – Implement SQL Profiles and test Only sessions with “TEST” sqltune_category see these Profiles - private scope!! alter session set sqltune_category= ‘DEFAULT’; -- Now SQL Profiles visible globally to all sessions Similarly for Invisible Indexes, Pending Stats Use SPA time limit to control resource usage Test during maintenance window or non-peak activity when spare resources are available

Using SPA on Production: Evaluating Optimizer Statistics Refresh and other changes Scenario: Can I use SPA to check if any SQL statements regressed due to optimizer statistics refresh on my 10.2/11g production databases? If so, how? Goal: Assess impact of optimizer statistics gathering on SQL workload performance on production system using SPA & make sure are no negative effects of the change

Evaluating Optimizer Statistics Refresh Assumptions – Statistics refreshed periodically through custom jobs – No test system available, so evaluation is done on production – Should impact end-users minimally – Test using optimizer pending statistics feature Use SPA remote trials capability (generate plan and test execute) to evaluate statistics refresh on 10.2/11g production database Analyze SPA report and take appropriate action – Overall improvement but few SQL regressions Solution: Use SQL Profiles or Plan Management – No improvement and many regressions Solution: Revert to old statistics: Use optimizer statistics retention/history feature. Alternatively, configure optimizer statistics appropriately* – For Oracle Database 11g, “publish pending” statistics after evaluation of statistics OBE Tutorial on OTN: Gathering and Publishing Stats Independently

Using SPA on Production: Evaluating Optimizer Statistics Refresh Production Database (10.2/11g) 11g SPA System 1.Capture SQL workload to STS Prod: Before Stats Prod: Stats Refreshed Evaluate Opt Statistics Refresh 5. Publish Pending Stats and Remediate Regressions Remotely Build SQL Trials No Test Database Used!! 3. Gather Pending Stats 2. Import STS 4.Use SPA to detect performance changes No app schema/data necessary Not Mandatory for 11g db Repository for many tests!

Evaluating Optimizer Statistics Refresh Tips! – On production, first use SPA to generate execution plans only, then test-execute SQLs with changed plans – If you’re creating remote trials, you will need a logon trigger to set optimizer_use_pending_statistics = TRUE private to the second trial (SPA establishes the connection itself, over db link, so you cannot run alter session yourself) – To test-execute only those SQLs with changed plans, subset your STS after doing trial 2, then do a new SPA experiment on that STS Script to subset STS is on Notes slide

Usage Scenario: End-to-End Case Study for 10.2  11g Upgrade

10.2  11g DB Upgrade Using Enterprise Manager Grid Control (EMGC) Scenario: I want to upgrade from 10.2 to 11g database release to benefit from 11g functionality. How can I best accomplish the upgrade? Goal: Assess impact of upgrade on SQL workload performance using SPA so that there are no surprises after upgrade. Once migrated to 11g new features can be enabled one at a time. Use EMGC for this purpose…

10.2  11g DB Upgrade Production Database 11g SPA System 1.Capture SQL workload to STS Upgrade Test Database Test DB (11g) Upgrade Test DB (10.2) Collect execution stats 3. Establish 10.2 and 11g Trials 4. Compare performance and generate SPA report Send SQL for Remote Execution Prod DB (10.2) 2. Transport STS 5. Deploy Tuning and Change to Prod

10.2  11g DB Upgrade (1) Capture Workload to STS Steps 1 : Capture workload into STS through Incremental Capture Workload into STS: Preferred method Other sources for STS also possible: Top SQL in AWR / AWR Baseline

10.2  11g DB Upgrade (1) Capture Workload to STS

10.2  11g Upgrade 1.Capture SQL workload to STS 3. Establish 10.2 and 11g Trials 2. Transport STS 4. Compare performance and Generate SPA report 5. Deploy Tuning and Change to Prod

Step 2: Copy STS to SPA system Setup Test DB (Copy of Prod) – 10.2 Upgrade Test DB from 10.2 to 11g 10.2  11g DB Upgrade (2) Transport STS

10.2  11g DB Upgrade 1.Capture SQL workload to STS 3. Establish 10.2 and 11g Trials 2. Transport STS 4. Compare performance and Generate SPA report 5. Deploy Tuning and Change to Prod

10.2  11g DB Upgrade (3) Establish 10.2 and 11g Trials

10.2  11g Upgrade 1.Capture SQL workload to STS 3. Establish 10.2 and 11g Trials 2. Transport STS 4. Compare Performance, Generate SPA Report 5. Tune Regressions, Deploy Tuning and Change to Prod

10.2  11g DB Upgrade (4) Compare Performance and Generate Report *5* Note tuning/regression fix is done on remote test system that is being upgraded

SPA Report Regressed SQL Statements

10.2  11g Upgrade 1.Capture SQL workload to STS 3. Establish 10.2 and 11g Trials 2. Transport STS 4. Compare performance and Generate SPA report 5. Tune Regressions, Deploy Tuning and Change to Prod

10.2  11g DB Upgrade (5) Regression Remediation If SPA system has application data/schema, tuning can be done locally on the same DB If a separate SPA system is used, manually* subset SQL into a separate STS and then use EM to transport it to remote DB Create SQL Plan Baselines: Helps revert to previously known, stable plans SQL Tuning Advisor: Helps explore better execution plans All regressed SQL are targeted automatically for remediation * Code snippet in Real Application Testing Users Guide (11.2), Chapter 11 Page 23

10.2  11g DB Upgrade (5) Regression Remediation

10.2  11g DB Upgrade (5) Deploy Tuning and Change in Production

10.2  11g Upgrade 1.Capture SQL workload to STS 3. Establish 10.2 and 11g Trials 2. Transport STS 4. Compare performance and Generate SPA report 5. Tune Regressions, Deploy Tuning and Change to Prod

SPA Exadata Simulation: Estimating Exadata Server Performance Gains

Predicting performance gains with SPA Existing SPA and Database Replay functionality can be used to compare non-Exadata to Exadata configurations – SPA: Unit test to find SQL response time gains – DB Replay: Stress test with concurrency to find throughput gains – Measure improvements for your workload – This approach requires you to provision Exadata HW Oracle Database Release : Adds SPA functionality to simulate Exadata on existing hardware to predict gains Oracle Database Release 11.2: Adds SPA GUI support Simulation measures reduction in I/O interconnect usage that will in turn, reduce IO and CPU consumed on the DB server

SPA Exadata Simulation Workflow SPA Exadata Simulation builds two SQL Trials: Trial 1: Current configuration with No Exadata Trial 2: Current configuration with Exadata simulation Comparison metric – I/O Interconnect Bytes – Trial 1 value = I/O Interconnect (disk) bytes – Trial 2 value is reduced depending on SQL operation eligibility (for full table scans, index full scans, etc.) – Plans will not change between trials

SPA Exadata Simulation Workflow

SPA Exadata Simulation: Report

SPA Report: SQL Details

SPA Enhancements in Oracle Database 11g Release 2

SPA Enhancements: Oracle Database 11g Release 2 Multiple test executes for better trial accuracy – first execution ignored, averaged stats Alternate Plans: New recommendation added for regression remediation – If a better execution plan was noticed in AWR or baseline SQL Trial then a SQL Plan Baseline can be created from it Active Reports – New interactive, offline reports based on Adobe Flash Player UI – Customers can share reports internally or with Oracle Support Save, , View Reports Support can diagnose problems more efficiently Get EM UI without installing EM – useful for packaged apps and internal development teams – SPA Active Report Example SPA Active Report Example

SPA Enhancements: Oracle Database 11g Release 2 Using SPA With Other Testing Tools – Build Trials from STS Allows comparing two different STS and generate SPA report – Eliminates re-executing SQL for trial data – Performance statistics picked up from the STS – Multiple plans even those with different binds/env picked up for comparison Use cases: Perform SQL-centric analysis – Database Replay SQL workload capture into STS-1 during Database Replay - Workload Capture STS-2 during Database Replay – Workload Replay Use SPA to build trials from STS-1 and STS-2 and generate report – Similarly with Oracle Application Testing Suite or home-grown scripts Reporting: SPA Report + Additional information – Common SQL, Missing/New SQL, Plan Changes – Overall Workload and Individual SQL Statistics – Available in 11.2 database release, API only

Conclusion SPA provides comprehensive and easy-to-use solution for SQL workload testing SPA can be used for many changes both test and production environments Helps adopt technology faster by significantly cutting down testing costs and production deployment risk With SPA and Real Application Testing businesses can be stay competitive and improve profitability

10.2  11g DB Upgrade (1) Capture Workload to STS

No EM in your environment, use API: EXEC DBMS_SQLTUNE.CAPTURE_CURSOR_CACHE_SQLSET( sqlset_name => 'my_sts', time_limit => 24*60, repeat_interval => 5);

10.2  11g DB Upgrade (2) Transport STS Make sure directory object exists on Prod and Test DB Make sure all the sub-steps succeed